AUSTIN — Seven school districts took the state to court Tuesday, asking for a fairer school finance system, and hundreds more are expected to join them in a suit that could force lawmakers to again overhaul how Texas funds public education.

The districts, two taxpayers, a parent and a newly formed Texas Taxpayer & Student Fairness Coalition asked a state district court in Travis County to force an overhaul by threatening to halt distribution of state school aid. A property owner in Kaufman’s school district is among the plaintiffs.

The current school finance structure, which lawmakers remodeled in 2006, is “unsustainable, indefensible, inefficient and unacceptably inequitable,” the plaintiffs said.

State officials did not immediately respond. They will defend the state’s school finance system in court, aiming to convince judges that the state meets the Texas Constitution’s requirement for equitable funding. Legal wrangling over the extraordinarily complicated system could take years.

The plaintiffs noted that some districts are getting tens of millions more dollars per year from the state than districts of similar size.

Last year, Austin’s school district, which is comparable in size to Fort Worth’s, received $1,000 more per weighted student, even though both districts had the same basic tax rate of $1 per $100 of property valuation, the suit said.

“This difference in funding provides Austin ISD with $100 million per year more than the same tax effort makes available to Fort Worth ISD,” the plaintiffs argued.

Fort Worth and Austin “are not isolated examples, nor do they present the worst comparisons,” said the suit, ticking off gaps of nearly $1,800 per student between two Bexar County districts, and $4,500 between two in West Texas.

The suit, one of as many as three expected to be filed in coming weeks, named state Education Commissioner Robert Scott, Comptroller Susan Combs and the State Board of Education as defendants.

“We are still analyzing the new school finance lawsuit,” said Texas Education Agency spokeswoman Debbie Ratcliffe, who works for Scott and the board. Ratcliffe said the agency and Attorney General Greg Abbott’s office will prepare an official response.

“Obviously, this is an issue that the courts and the Legislature will ultimately have to resolve,” she said.

Ricky Dailey, spokesman for the Texas School Coalition, a group of property-wealthy districts, said some of the disparities can be explained by mineral wealth and “historical differences.”

The suit brings up Fort Worth and Austin but doesn’t mention that “Austin had chosen to keep class sizes low and taxes high” by 2006, when lawmakers reduced school property tax rates by one-third, Dailey said.

Members of the wealthy-district coalition also plan to file a suit soon, he said. Dailey said it will in part echo the initial suit’s claim that the system is broken, mainly by stressing that districts are bumping up against a tax-rate cap that robs them of “meaningful discretion,” which also would violate the Texas Constitution.

The suit filed on Tuesday was mainly organized by the Equity Center, a nonprofit alliance of nearly 700 school districts that advocates for equal funding.

Wayne Pierce, the center’s executive director, said more than 150 districts are members of the newly formed fairness coalition that is the lead plaintiff. Pierce said he expects another 150 will join by the time the lawsuit goes to trial about a year from now.

“We have an irrational funding system,” said Pierce, a former superintendent of the Kaufman district.

Last year, more than 200 districts set their maintenance and operations tax rates at the maximum: — $1.17 per $100 of property valuation, he said.

Because of deep cuts to education that lawmakers approved last spring, such districts won’t be able to offset state funding reductions and keep up with rising student-achievement standards set by the Legislature, Pierce said.

“They can’t raise their tax rate. They’ve got more responsibility … and the state cut their funding, even though [lawmakers] had money in the rainy day fund and they could have at least not cut the districts on the bottom” in property wealth, he said.

Some GOP school policy writers in the Legislature have said that while they regret they couldn’t improve the system’s equity, they faced a massive budget shortfall and believe the overall system can still be defended in court successfully.

Most money for education comes from state payments to school districts and local property taxes, and the federal government provides some, too. The inequity between what districts have to spend comes mostly from differences in their property wealth. Changes made by the Legislature five years ago, after the last major school finance lawsuit, made those disparities worse.